Ahh, it's a little confusing i'll admit. Those options are only for text export. The category bar between saving as binary and saving as text is supposed to indicate that, but it's not super evident. Neither is it the first time this is brought up, haha.
Also worth noting; whenever a .map binary is saved; the last 4 bytes tell the dimensions of that map; counted in tiles.
.nams on the other hand, as standardized by NES emulators, are always 32x30 - so 960 bytes for tile ID elements, 64 bytes for attribute cells.